Step 1 - Export your data from LogTen Pro
Reports -> Exporters -> Export Flights (Tab)
Save the .txt file to your computer.
Step 2 - Copy/Paste each column
Open the exported .txt file in Excel (or whichever spreadsheet program you use).
NOTE: Simply opening the .txt file with a .txt viewer will not allow you to copy the data appropriately.
Copy and Paste each column into your logbook, one at a time, to ensure the data is preserved.
In order to maintain the same formatting/design in your logbook, click the PASTE icon and select "Values Only" (this will ensure no formatting is inadvertantly copied).
By default, Excel Pilot Logbook has 1000 rows. If you need to add more, please see How to Add more Logbook Entries.